This problem, seems to be worst around this estate and also down this end of Leasowe RD/Pasture Rd. There used to be an Orange mast on Tarran Industrial Estate. EE discontinued it and the signal dropped from 5bars to one bar, unless I stand on the back bedroom wihdow sill!
The other problem is pure BT and is connected with the copper cabling between the house and the local exchange. But it is alao time related and is,I believe, to do with the way BT controls the access to its system!